API Overview

The SPF API consists of ten endpoints that allow customers to determine and complete applicable payroll withholding forms for employees.


  • Build your own user experience (UX) and consume the Symmetry Payroll Forms API (ideal for custom branding and maintaining your application’s look and feel).
  • Pass the employee and employer address information to the SPF API via JSON and the API takes care of determining flows, forms, and tax parameters.
  • Capture and store the form answers before passing the information to the SPF API which returns the completed PDF (Base64 encoded) and relevant tax parameters.
  • Print, email, or save the completed PDF as you choose and store the tax parameters in your payroll system.


SPF API is compliant for both United States and Canada and we maintain the latest federal, state, local, and provincial forms.

Implementation Options

Like with our hosted and on-premise versions, the SPF API supports two different implementation options:

  • Guided Process: Ideal for employee onboarding — employees are coached through an automated process ensuring forms are correct and complete.
  • Choose Mode Process: Ideal for companies and employees who know the exact forms they need — gives employees the ability to select forms at will while field validation ensures employees complete forms accurately.

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